Basket assembly, spines, and electrodes for a catheter, and methods of the same

This application claims, under 35 U.S.C. § 119(e), priority to and the benefit of U.S. Provisional Patent Application No. 63/385,741, filed Dec. 1, 2022, the entire contents of which are incorporated herein by reference.

The present invention relates generally to medical devices, and in particular catheters with electrodes, and further relates to, but not exclusively, catheters suitable for use to induce irreversible electroporation (IRE) of cardiac tissues.

Cardiac arrhythmias, such as atrial fibrillation (AF), occur when regions of cardiac tissue abnormally conduct electric signals to adjacent tissue. This disrupts the normal cardiac cycle and causes asynchronous rhythm. Certain procedures exist for treating arrhythmia, including surgically disrupting the origin of the signals causing the arrhythmia and disrupting the conducting pathway for such signals. By selectively ablating cardiac tissue by application of energy via a catheter, it is sometimes possible to cease or modify the propagation of unwanted electrical signals from one portion of the heart to another.

Many current ablation approaches in the art utilize radiofrequency (RF) electrical energy to heat tissue. RF ablation can have certain risks related to thermal heating which can lead to tissue charring, burning, steam pop, phrenic nerve palsy, pulmonary vein stenosis, and esophageal fistula.

Cryoablation is an alternative approach to RF ablation that generally reduces thermal risks associated with RF ablation. Maneuvering cryoablation devices and selectively applying cryoablation, however, is generally more challenging compared to RF ablation; therefore cryoablation is not viable in certain anatomical geometries which may be reached by electrical ablation devices.

Some ablation approaches use irreversible electroporation (IRE) to ablate cardiac tissue using nonthermal ablation methods. IRE delivers short pulses of high voltage to tissues and generates an unrecoverable permeabilization of cell membranes. Delivery of IRE energy to tissues using multi-electrode catheters was previously proposed in the patent literature. Examples of systems and devices configured for IRE ablation are disclosed in U.S. Patent Pub. No. 2021/0169550A1, 2021/0169567A1, 2021/0169568A1, 2021/0161592A1, 2021/0196372A1, 2021/0177503A1, and 2021/0186604A1, each of which are incorporated herein by reference and attached in the Appendix hereto.

Regions of cardiac tissue can be mapped by a catheter to identify the abnormal electrical signals. The same or different catheter can be used to perform ablation. Some example catheters include a number of spines with electrodes positioned thereon. The electrodes are generally attached to the spines and secured in place by soldering, welding, or using an adhesive. Due to the small size of the spines and the electrodes, however, soldering, welding, or adhering the electrodes to the spines can be a difficult task, increasing the manufacturing time and cost and the chances that the electrode fails due to an improper bond or misalignment. What is needed, therefore, are systems and methods of attaching an electrode to a spine of a basket assembly without the need for soldering, welding, or using adhesive.

There is provided, in accordance with an example of the present invention, a spine member for an end effector for an expendable basket assembly for a medical probe. The spine member may extend along a longitudinal axis from a proximal end to a distal end. The spine member may include a unidirectional proximal stop member to allow an electrode to slide in a direction distally but not proximally and a distal stop to prevent an electrode from sliding past. In this way, the presently disclosed technology can be used to secure the electrodes to the spines without requiring solder, weld, or adhesives.

There is provided, in accordance with an example of the present invention, an expandable basket assembly for a medical probe. The expandable basket assembly may include a plurality of spines configured to bow radially outward from a central axis when the expandable basket assembly is transitioned from a collapsed form to an expanded form. Each spine of the plurality of spines may include (i) a proximal electrode stop configured to allow a distal electrode to slide distally on each spine past the proximal electrode stop but prevent a proximal electrode from sliding distally past the proximal electrode stop and (ii) a distal electrode stop configured to prevent the distal electrode from sliding distally past the distal electrode stop.

The proximal electrode stop may include a pair of first proximal protrusions extending from opposing sides of each spine with a first proximal facing portion angled away from a proximal end of each spine and a first distal facing portion approximately parallel with the proximal end of each spine.

The proximal electrode stop may also include a pair of second proximal protrusions extending from the opposing sides of each spine with second proximal facing portion angled away from the proximal end of each spine.

The proximal electrode stop may include a bulged portion in a default state that is configured to retain an electrode in place in a default state and configured to allow an electrode to travel distally along each spine when the respective spine is deformed.

The proximal electrode stop may include a first pair of lateral cutouts, a second pair of lateral cutouts, a first coil, and a second coil. The first pair of lateral cutouts may be configured to receive the first coil and the second pair of lateral cutouts may be configured to receive the second coil. The first and second coils may be configured to restrain the proximal electrode positioned therebetween from sliding distally or proximally after the distal electrode is positioned distally past the proximal electrode stop.

The distal electrode stop may include a third pair of lateral cutouts, a fourth pair of lateral cutouts, and a third coil, a fourth coil. The third pair of lateral cutouts may be configured to receive the third coil and the fourth pair of lateral cutouts configured to receive the fourth coil. The third and fourth coils may be configured to restrain the distal electrode positioned therebetween from sliding distally or proximally.

The proximal electrode stop may include a proximal diamond portion, a distal diamond portion, and a diamond intersection connected to the proximal and distal diamond portions.

In a default state, the proximal diamond portion may be configured to prevent the proximal electrode from sliding proximally. In the default state, the distal diamond portion may be configured to prevent the proximal electrode from sliding distally.

In an expanded state, the proximal diamond portion is configured to allow the distal electrode to slide distally. Also in the expanded state, the distal diamond portion is configured to allow the distal electrode to slide distally.

The proximal electrode stop may include a pair of proximal protrusions. The pair of proximal protrusions may include a proximal face angled away from the proximal end of the spine and a distal face substantially parallel to the proximal end of the spine. The proximal electrode stop may also include a distal aperture configured to receive a protrusion of a retainer rivet.

The retainer rivet may include a polymer.

The proximal electrode stop may include a shim distal to the pair of first proximal protrusions that is configured to insert into a lumen of the proximal electrode and prevent distal movement of the proximal electrode.

The proximal electrode stop may include a first shim that is configured to insert into a lumen of the proximal electrode and prevent proximal movement of the proximal electrode. The proximal electrode may also include a second shim distal to the pair of first proximal protrusions that is configured to insert into the lumen of the proximal electrode and prevent distal movement of the proximal electrode.

The proximal electrode stop may include a pair of first proximal protrusions extending from opposing sides of each spine with a first proximal facing portion angled away from a proximal end of each spine and a first distal facing portion approximately perpendicular with the proximal end of each spine. The distal electrode stop may include a pair of distal protrusions extending from opposing sides of each spine with a proximal facing portion substantially perpendicular with the proximal end of each spine.

The expandable basket assembly may include a flexible member between the proximal electrode and the distal electrode.

The flexible member may be configured to prevent proximal movement of the distal electrode and distal movement of the proximal electrode.

Each spine may include a first width at the proximal electrode stop and second width at the distal electrode stop. The second width may be greater than the first width.

Each spine may gradually change from the first width to the second width.

The proximal electrode may include a first lumen with a first diameter less than or equal to the first width such that it cannot move distally past the proximal electrode stop. The distal electrode may include a second lumen with a second diameter greater than the first width but less than or equal to the second width such that it cannot move distally past the distal electrode stop when placed on each spine.

The expandable basket assembly may include the proximal electrode that may include a first lumen gradually changing from a first diameter to a second diameter. The first diameter may be less than or equal to the first width and the second diameter may be greater than the first diameter and less than or equal to the second width. The distal electrode may have a second lumen gradually changing from the second diameter to the first diameter.

Each spine may include (i) a first width at the proximal end for a first length extending away from the proximal end and (ii) a second width for a second length. The second width may be greater than the first width. Each spine may also include a third width for a third length and the third width may be greater than the second width. The first width may gradually increase to the second width over a fourth length and the second width may gradually increase to the third width over a fifth length.

The proximal electrode stop may a pair of first proximal arms extending from opposing sides of each spine angled away from the proximal end of each spine, the pair of arms are configured to close such that the distal electrode can slide over the pair of arms while also forming a pocket retaining the proximal electrode when the proximal electrode moves proximally.

Each spine may include (i) a first portion configured to receive and connect with the proximal electrode and having a first width, (ii) a second portion having a second width, and (iii) a third portion having a third width and configured to receive and connect with the distal electrode. The second width may be greater than the first and third width.

Each spine of the plurality of spines may include one or more apertures extending therethrough from a first side of the spine to a second side of the spine. The one or more apertures configured to receive a locking stub of the proximal or distal electrode such that when the proximal or distal electrode is mechanically coupled to the spine, the locking stub may extend through the aperture preventing the proximal and distal electrode from sliding distally or proximally along the spine.

The proximal and distal electrodes may each define a lumen extending therethrough and a locking stub extending at least partially into the lumen.

Each spine of the plurality of spines may pass through a lumen of the proximal and distal electrodes.

There is provided, in accordance with an example of the present invention, an expandable basket assembly for a medical probe. The expandable basket assembly may include a plurality of electrodes and a plurality of spines configured to bow radially outward from a central axis when the expandable basket assembly is transitioned from a collapsed form to an expanded form. Each spine of the plurality of spines may include a plurality of electrode extension portions extending radially from each spine. Each electrode extension portion may include a band to receive and retain an electrode of the plurality of electrodes.

The plurality of electrodes may include platinum.

The plurality of electrode extension portions may include an adjustable height.

There is provided, in accordance with an example of the present invention, a method of constructing a medical probe. The method may include aligning a spine of an expandable basket assembly with an electrode of the expandable basket assembly, the spine comprising a proximal end, a distal end, and an aperture extending therethrough. The method may also include inserting the spine into a lumen of the electrode and aligning a locking stub of the electrode with the aperture. The method may also include crimping the electrode onto the spine such that the locking stub extends at least partially into the aperture to prevent the electrode from sliding proximally or distally along the spine.

The spine may also include an insulative material configured to electrically isolate the spine from the electrode.

The expandable basket assembly may include an insulative material disposed between the electrode and the spine to electrically isolate the electrode from the spine.

The lumen may include a first lumen. The method may also include (i) aligning an electrically conductive member of the medical probe with a second lumen of the electrode, (ii) inserting the electrically conductive member into the second lumen, and (iii) coupling the electrically conductive member to the electrode such that the electrically conductive member is in electrical communication with the electrode.

The electrically conductive member may be insulated from the spine.

An interface between the locking stub of the electrode and the spine at the aperture comprises an interference fitting.

The spine may include a material selected from a group consisting of nitinol, cobalt chromium, stainless steel, titanium.

The spine may include a polymer material.

The aperture of the spine comprises a first aperture. The spine may include a second aperture. The method may further include (i) aligning the spine with a second electrode of the expandable basket assembly, (ii) inserting the spine into a lumen of the second electrode, (iii) aligning a locking stub of the second electrode with the second aperture, and (iv) crimping the second electrode onto the spine such that the locking stub extends at least partially into the second aperture to prevent the second electrode from sliding proximally or distally along the spine.

There is provided, in accordance with an example of the present invention, a method of constructing a medical probe. The method may include (i) sliding a distal electrode from a proximal end of a spine past a proximal electrode position, (ii) sliding a proximal electrode from the proximal end to the proximal electrode position, and (iii) securing the proximal and distal electrode to the spine.

The following detailed description should be read with reference to the drawings, in which like elements in different drawings are identically numbered. The drawings, which are not necessarily to scale, depict selected embodiments and are not intended to limit the scope of the invention. The detailed description illustrates by way of example, not by way of limitation, the principles of the invention. This description will clearly enable one skilled in the art to make and use the invention, and describes several embodiments, adaptations, variations, alternatives and uses of the invention, including what is presently believed to be the best mode of carrying out the invention.

As used herein, the terms “about” or “approximately” for any numerical values or ranges indicate a suitable dimensional tolerance that allows the part or collection of components to function for its intended purpose as described herein. More specifically, “about” or “approximately” may refer to the range of values ±10% of the recited value, e.g. “about 90%” may refer to the range of values from 81% to 99%. In addition, as used herein, the terms “patient,” “host,” “user,” and “subject” refer to any human or animal subject and are not intended to limit the systems or methods to human use, although use of the subject invention in a human patient represents a preferred embodiment. As well, the term “proximal” indicates a location closer to the operator or physician whereas “distal” indicates a location further away to the operator or physician.

As discussed herein, vasculature of a “patient,” “host.” “user,” and “subject” can be vasculature of a human or any animal. It should be appreciated that an animal can be a variety of any applicable type, including, but not limited thereto, mammal, veterinarian animal, livestock animal or pet type animal, etc. As an example, the animal can be a laboratory animal specifically selected to have certain characteristics similar to a human (e.g., rat, dog, pig, monkey, or the like). It should be appreciated that the subject can be any applicable human patient, for example.